Undersea optical fiber communication systems typically include optical fiber cables laid along the ocean floor, sometimes for hundreds or thousands of kilometers. Such systems may include a main trunk path extending between remote cable stations. The trunk path may include numerous coupled optical fiber cables, one or more repeaters, e.g. optical amplifier repeaters, and other optical/electrical equipment. At each end of the trunk path, the optical fiber cable extends out of the ocean, onto land, and eventually into a cable station. The cable station may be configured for transmitting and receiving optical signals along the path and to/from other destinations using terrestrial communications networks.
Such undersea systems may also include one or more branch segments coupled to the trunk path by a submarine branching unit. A branch segment typically includes a plurality of coupled optical fiber cables and one or more repeaters, and extends from the branching unit, onto land, and to an associated branch segment cable station. The branch segment cable station may be configured for transmitting and receiving signals along the branch segment and to/from other destinations using terrestrial communications networks.
The optical repeaters coupled along the trunk path and branch segments receive incoming wavelengths of light from the optical cables coupled thereto, amplify the light using, for example, erbium doped fiber and an optical pump, and then transmit the amplified light on the next section of optical cable in the segment. Numerous optical repeater configurations are known to those skilled in the art. Such optical repeaters require electrical power to operate, but are not typically located near a power source. As such, electrical power is provided to each of the repeaters via the power conductor of the optical fiber cable connected thereto.
All of the repeaters in a segment may be powered in series by a current supplied on the power conductors of the cables forming the segment. The current supplied on the cable power conductors is provided by power feed equipment (PFE) located at a cable station. For the trunk path, the cable power conductor may be connected to a positive PFE terminal at one cable station and to a negative PFE terminal at the cable station at the opposite end of the path. For a branch segment, the cable power conductor may be connected to a negative PFE terminal at the cable station coupled to the end of the branch segment and may be connected to a positive PFE terminal of one of the trunk path cable stations through connections in the branching unit.
Conventional configurations require PFE at each cable station associated with the trunk path and each branch segment for providing electrical power to repeaters within the path/segments. Each trunk path and segment is installed having the necessary PFE and repeaters to sustain communications between the cable stations connected thereto. The high cost of installing and operating trunk paths and segments including such equipment can limit the number and configuration of the path/segments for a particular system. Accordingly, there is a need for a configuration, method and system which reduces the cost of undersea communication systems.